JPH07506454A - Dispersion spinning method for coated rod-in-tube superconducting composite - Google Patents

Abstract

Methods of forming composite articles of superconducting materials and metal are disclosed. The composite articles are formed by applying a mixture of metal and binder to a ceramic oxide preform. The coated preform is heat treated to provide composite articles of superconducting ceramic and metal.

Description

[Detailed description of the invention] Dispersion spinning method for coated rod-in-tube superconducting composite Field of the invention The present invention is generally directed to the production of composite materials. In more detail, the book The invention is intended for the production of superconducting wires.

Background of the invention High-temperature superconductors, ie, superconductors with critical temperatures on the order of 90 degrees, are described by WU Ike, Ph. ys, Rev. Left, 58.908-910 (1987). Ru. These high temperature superconductors are based on the Y-Ba-Cu-0 system. US Patent No. No. 4,929.594 contains the formula T12Ba2Cu064 [wherein X is from 0 to about A superconducting composition composed of a crystalline phase represented by [15] is disclosed. , which indicates temperatures above about 90 degrees. Subramanian et al., 5cien ce 239.1015-1017 (1988), formula B i zs r A material represented by 3-tc　a　*Cu　20B-F is disclosed, which is It shows a resistance drop at about 116 degrees and an apparent zero resistance at 91 degrees.

A wide variety of superconducting material applications have been developed. These applications include power transfer and and high-speed computer electronics. Superconductor materials are mainly in the form of sintered crystals This is because long products like wire are difficult to manufacture. This is because, at the same time, it exhibits non-uniform characteristics. U.S. Patent No. 4.980.96 = 4 In the known superconducting wire manufacturing technology as shown in No. (wder-in-tube) technology is used. This technology is carried out in a metal tube. The tube was filled with powder of superconductor material and sealed (with a predetermined wire size). The process involves cold stretching the sealed metal tube until the desired temperature is achieved. This spread Heat treating the drawn wire ensures crystallinity for this superconductor material.

However, the wires obtained with this technique are short in length and exhibit non-uniform properties. .

Improvements to in-tube powder technology have been published in European Patent Application No. 0292-385. It is written in the number. This publication involves mixing superconducting oxide powder with a binder. While kneading materials, the resulting kneaded paste is produced using an extruder or other equipment. By shaping, elongated pre-form The fabrication of elongated superconducting composites via producing It is. The binder is removed by continuously heating the preform. Next After wrapping the metal notebook around this pre-formed body, high-temperature sintering is performed. this Although the superconducting wires obtained with the method are longer and exhibit somewhat higher uniformity, This method may change the anorexia content of the resulting sintered ceramic. , thus the superconducting properties may be sacrificed.

European patent application publication no. A method of forming conductive ceramics is presented. In one embodiment, upon heating prior to the preforming of a plastic composition consisting of a polymer, a plasticizer and a ceramic material; By bonding the body with a blend of metals, polymers, and plasticizers, This results in a ceramic article in which the metal coating sinters when heated. However, this In this method, the material present between the superconducting material and the metal coating is Easily causes bleeding.

Thus, the disadvantages of prior art methods are avoided while providing improved length and uniformity. However, metal coatings of elongated superconducting ceramics have shown effectiveness in wire applications. There is a need for a method of manufacturing a counterfeit product.

Summary of the invention The present invention provides a long (extended) superconducting composite article containing a superconducting material within a metal coating. A continuous method of manufacturing is provided. This method uses ceramic powder and organic bond. This involves producing a long (elongated) molded product from the mixture with the mixture solution. An organic binder different from the binder solution used in this ceramic powder was added to the elongated product. Coating a mixture of solution and metal powder. By heating this metal-coated item, By burning out the organic binder and crystallizing the ceramic powder. This creates an elongated superconducting composite that is coated with metal.

Illustration description Figure 1 shows a spin cell used to produce ceramic fibers that are later coated with metal. FIG.

Figure 2 shows an apparatus for producing metal-coated superconducting ceramic wires. It is a schematic diagram.

FIG. 3 is a schematic cross-sectional view of a superconducting wire according to the invention.

Detailed description of the invention Superconducting materials that have been shown to be effective in the practice of the present invention have a critical temperature (T, ), i.e., a resistance Ceramic whose temperature drops to essentially zero is preferably about 77 degrees Celsius or higher. Materials included. Such materials are described, for example, in Song et al., J. Matc. r-,, Res　s,　, Volume 5, No. 1.27-32　(1990) and Pi er'je et al., J, of Δpp1. Phys, 68.2296-2303 (1990). Ceramic materials with T, >77 degrees, Y-13a-Cu-0 system (this includes Y+Ba2Cu, 0); T l-Ba-Cu-0 system, for example TI, Ba, Cu0.4° [where x=0 to 0.5]; Bi-3r-Ca-Cu-0 system, for example Bi2Sr 3-aCa, Cuzoa-y [where x=0.4 to 0.9 and Q< y<11; and B1-Pb-3r-Ca-Cu-0 system, for example Bi+ sP bo4S r t aCat oc LIt, aOs, z*w and B it, mPbo4srt ocaz, tcus. ola, s+t [where, x=0.1 to 0.5].

Generally, the superconducting wire material provided by the present invention is prepared by combining a solution of an organic binder and a superconducting cell. It can be manufactured by mixing with lamic materials. The resulting superconducting cera The mixture of metal and binder is formed to form a preform, which is then combined with metal and binder. A superconducting ceramic-metal composite can be obtained by coating with a mixture of Ru. The solvent used in the binder solution containing this metal and binder mixture is This is different from the solvent used in the binder used in ceramics. typically , using either solution or vapor deposition methods, this ceramic gold r! ! 4 complex The metal coating can be attached to. This metal coated ceramic is heat treated By removing the organic binder, the metal is coated with a long elongated Produce superconducting products.

Generally, both ceramic and metallic materials are used with commercially available Binders or mixtures thereof can be used. However, preferably , the organic binder used is one that burns off without leaving any residue. Ru. Superconducting ceramic metal acid cellulose, poly(vinyl alcohol) according to the invention ), poly(ethylene oxide), poly(vinyl butyral), poly(methyl methacrylic acid), poly(methyl methacrylate), methylcellulose, poly( isobutylene) and poly(propylene carbonate), but preferably is polyethylene oxide, most preferably poly(propylene carbonate). Ru.

Preferably, both the ceramic oxide and the metal powder are essentially the same. Use organic binders. However, these binders cannot be dissolved in different solvents. With the condition that the binder used is the ceramic 5. There is a difference between powder and metal coating. You may

Based on the total volume of this binder and ceramic material (excluding any solvent) 20 to 80% of the binder present in the ceramic and binder mixture The amount of can be varied. Preferably, the amount of binder varies from 30 to 45% by volume. obtain. Similarly, 20 to 80% by volume is present in the binder and metal mixture. The amount of binder present can be varied. Preferably, 30 to 45% of the binder and metal The volume percent of binder present in the mixture can be varied.

To obtain a dense mixture of either ceramic, porcelain or metal powder with an organic binder, binds the binder with an organic solvent that is at least partially a solvent for the binder. Mix with. Solvents useful in the present invention include both polar and non-polar solvents.

Therefore, useful solvents include ethylene glycol, methyl ethyl ketone, Contains xanone, acetone, ethyl acetate, methanol, glycerol and water , preferably methyl ethyl ketone. However, when mixed with this metal powder, The solvent used in the organic binder used with the ceramic oxide is It is not a solvent for The solvent chosen should at least partially bind the binder. For example, polar binders should use polar solvents. Ru.

Generally, the solvent and binder mixture used with the ceramic and metal powders A surfactant may be mixed. Surfactants that can be used in the present invention include those with long chains. Organic acids such as oleic acid, polyacrylic acid, fatty acid esters and Contains fatty acid alkoxylates, preferably fatty acid alkoxylates. be.

The metal powder used to coat this ceramic preform contains a ductile conductive material. Materials may be included. Suitable metals include silver, gold, platinum, copper or mixtures thereof. preferably silver.

Composite of superconducting ceramic powder and organic binder coated with metal before heat treatment The product can be easily manufactured using known techniques suitable for manufacturing continuous ceramic fibers. can be built. For example, Wedde11, J, Text, In5t, 199 0.81, No. 4, pp. 333-359. Preferably, the method of FIG. Therefore, these composite products are manufactured.

Referring to FIG. 1, a mixture 10 of ceramic powder and an organic binder is placed in a spin cell 20. insert. The mixture 10 is passed through the nozzle 40 by pressing it with the piston 30. By extruding, an elongated continuous piece 50 is obtained. Wind onto the spool strip 50 by placing it in a container or an elongated container (not shown). can be collected.

FIG. 2 illustrates an apparatus for carrying out the method of the invention in continuous mode. In Figure 2 As shown, the ceramic and organic binder mixture 10 is placed into the spin cell 20. and by pushing it through the nozzle 40 by the piston 30, at least One ceramic fiber 62 is obtained. By passing the fibers 62 through a coating device 64. A coating consisting of a mixture of metal and organic binder is attached to the fibers 62. coating equipment 64 may be any commercially available coating equipment, for example C1cinnati Electric wire coater manufactured by Milicron or Fiber-reinforced plastic tow prepregers, etc. There may be.

Generally, a wide range of The metal and organic binder coating can be attached to the ceramic fiber 62 to a thickness of can. Varying the thickness of this metal coating from 20 x 10-’m to 2 x 10-3m This metal coating may be attached to the fiber 62, preferably 2×lO”m. After coating, the coated fibers are passed through an oven 80 to remove the organic binder. This method burns out the ceramic, crystallizes the ceramic, and increases the density of this metal coating. conduct. Generally, the heat treatment used in oven 80 involves bonding the bonding agent, the ceramic material, and the metal. The genus varies according to its specific composition. Following well-known operations, Its specific heat treatment temperature so as to obtain the desired superconducting phase of this ceramic oxide material temperature, atmosphere and time can be easily determined.

The resulting metal-coated superconducting ceramic fibers can be directly used in applications such as magnets and power lines. can be used. In addition, this metal-coated superconducting fiber can be applied to press rolls, plates or This fiber may be further densified by passing it through a die 90. This way If this is the case, the densified fibers are then passed through the second oven 82 again. By performing these further heat treatments, the current carrying capacity of this fiber can be increased. can be strengthened.

The resulting fibers are then collected using a collecting means such as spool 85 or similar device. You can collect fiber.

The metal-coated superconducting ceramic fibers of the present invention can be formed into various structures. However, here we use a single fiber or superconducting ceramic fiber. A large number of fibers are embedded in or coated with metal. Although the fiber 62 is round, , an ellipse, or a rectangle. FIG. 3 shows a cross-sectional view of the product 100. , here, a large number of ceramic fibers 62 are joined together to form a bundle, which is coated with metal 68.

The following non-limiting examples illustrate the invention.

Example 1 Production of ceramic and binder mixtures A mixture of ceramic oxide and binder is prepared as follows. In the first container, 10 g Bi,,Pb in 50 mL methyl ethyl ketone.

4Sr1.5ca2. By mixing ocuz, go coarse powder, the oxide powder Produce a dispersion. The commercially available surfactant SotexCW ( Two drops of Marton Chemical are mixed thoroughly with the above dispersion. second In a container, add 1.4 g of poly(propylene) to 20 mL of methyl ethyl ketone. carbonate) to prepare a solution containing the binder. This solution and the above oxide powder and a dispersion of the mixture. heating this mixture until it forms a gummy paste The methyl ethyl ketone is partially evaporated by .

Manufacture of elongated fibers The rubbery paste prepared above was prepared with an internal diameter of 1/2 inch as schematically shown in Figure 1. The spin cell is inserted into a standard stainless steel spin cell.

One tff person put a piston inside the spin cell to push out the paste. Afterwards, this spin cell is placed into a normal spin unit. manufacturing fibers A spinneret is added to this spin cell that allows for. The fiber is obtained from this spinneret. Adjust the speed of the spin unit so that

If the diameter of the spinneret opening used is 1/8 inch, the extruded fiber are collected on a 6 inch diameter bobbin. Spinneret with larger hole size When used, the extruded fibers can be collected on a tray. which In this case, the collected fibers are dried at room temperature.

Production of metal-coated ceramics 2.0 g of commercially available silver powder with an average molecular weight of about 600. 000 points Mix 0.24 g of ethylene oxide and 5 mL of methanol. and produced a silver paste for coating the ceramic fibers produced above. do.

After dipping the extruded ceramic fibers produced above into the silver paste, Homogenize that silver paste onto these ceramic fibers by evaporating the solvent coated with

Metal-coated cells produced by heat treatment and forming of metal-coated composite superconducting wires The organic binder was removed by heating the ramic fiber in air; Here, we start at 25°C and increase the temperature to 520'C at a rate of 3°C per stitch. After rising, the temperature is increased to 580° C. over a period of 5 hours. Next, at 5 o'clock Over time, this temperature was lowered to 520°C, and then 1 Lower to 20'C. This heat-treated material is then pressed between two metal plates. A metal-coated composite superconducting ceramic wire is produced by let This heat-treated and pressed wire is then dipped into silver paste. By re-coating this with Paint the opening. This recoated fiber was again used for the first low temperature cycle. Then, the organic binder is removed by heat treatment in air. This result The metal-coated ceramic wire is again pressed in the same manner as above. Then, that By heating the resulting wire, all remaining organic solvent is removed from it. By expelling from the oxide powder and silver paste, Bi1. aP bo, < Silver-coated superconducting ceramic represented by S r +, sCa t, oc ut, aO cause The temperature is measured per stitch in an atmosphere of 7% oxygen and 93% nitrogen. Raised from 25°C to 842°C at a rate of 3°C and held at 842°C for 25 hours. This heat treatment is carried out by doing this. Next, increase this temperature by 1 at 3°C per stitch. Lower the temperature to 20℃.

integrated reel Copy and translation of amendment) Submission (Article 184-8 of the Patent Law) October 26, 1994 Day

Claims (1)

[Claims] 1. In a method of manufacturing a ceramic composite article provided with a metal coating, The first mixture of the first organic binder solution and the ceramic powder is molded to form a long ceramic. The solution for the binder used in the first organic binder solution is A second mixture of a second organic binder solution and a metal in a different solvent than the preform. producing a coated ceramic preform by coating the feature; hand By heating the coated ceramic preform, a uniform gold layer is deposited thereon. producing a ceramic composite article having a metal coating. 2. The above ceramic is Bi1.6Pb0.4Sr1.6Ca2.0Cu2.8O 9.2+x and Bi1.8Pb0.4Sr2.0Ca2.2Cu3.0O10 ．． 3+x [where x=0.1 to 0.5] and the metal is a group of silver, gold, platinum, copper or mixtures thereof. The method of claim 1 selected from. 3. The above organic binders are cellulose acetate, cellulose acetate butyrate, poly(vinyl alcohol) poly(ethylene oxide), poly(vinyl butyral), poly(metal) methyl methacrylate), poly(methyl methacrylate), methyl cellulose, poly(methyl methacrylate), selected from the group of poly(isobutylene) and poly(propylene carbonate) A method according to any one of claims 1 or 2. 4. Claim 1 or 2, wherein the heating is at a temperature of 850°C or lower. Method. 5. The above ceramic is Bi1.6Pb0.4Sr1.6Ca2.0Cu2.8O 9.2+x [where x=0.1 to 0.5] and the metal is silver The method according to claim 3. 6. The above ceramic is Bi1.8Pb0.4Sr2.0Ca2.2Cu3.0O 10.3+x, where x=0.1 to 0.5. 7. Claims wherein said composite article comprises at least one ceramic preform Method 5. 8. said organic binder is in each of said first and second mixtures at least 10 volumes; 3. A method according to any one of claims 1 or 2, wherein the method is present in an amount of %. 9. the metal is silver and the binder is poly(propylene carbonate) A method according to any one of claims 5 and 6.